Undaria Pinnatifida (Wakame) Moderates Postprandial Glycaemia in Healthy Young Japanese Women

Background and Objectives: Brown seaweeds, such as Undaria pinnatifida (wakame), contain viscous dietary fiber sodium alginate, which can affect postprandial blood glucose concentrations. This study aimed to investigate the effects of wakame ingestion on postprandial blood glucose concentrations.

Methods and Study Design: In this randomized controlled cross-over study, healthy young women were recruited.The blood glucose concentrations were measured by self-monitoring at 0 min, and 15, 30, 45, 60, 90 and 120 min after consumed 150 g of rice with or without wakame (1.8 g or 4.0 g dried wakame).Glucose release rate of wakame extracts was measures using a cell-free artificial digestion test.

Results: The blood glucose concentrationat 15 min was significantly lower after consuming rice with 1.8 g of wakame than that of control (5.66±0.13vs 5.99±0.11 mmol/L, p=0.021, mean±SEM). Moreover, the blood glucose concentrations at 15 min (5.27±0.13 vs 5.63±0.12 mmol/L, p<0.001), 30 min (7.45±0.16 vs 7.95±0.18 mmol/L, p=0.002), and 45 min (7.75±0.22 vs 8.23±0.24 mmol/L, p=0.018) in consuming 4.0 g of wakame were all significantly lower than those of control. In the artificial digestion test, the glucose concentrations at 20 min and glucose release rate of all wakame extracts were significantly lower than those of the control (p<0.001). The soluble fraction, which contained sodium alginate, significantly inhibited the release of glucose. 

Conclusions: These results suggest that the highly viscous soluble fraction of wakame might increases the viscosity of the gastrointestinal contents and delays glucose absorption.

Keywords: Undaria pinnatifida, wakame, postprandial blood glucose, soluble dietary fiber, glucose release rate.